New NASA Research Shows Giant Asteroids Battered Early Earth

NASA / AMES Research Center logo.

July 30, 2014

New research shows that more than four billion years ago the surface of Earth was heavily reprocessed – or melted, mixed, and buried – as a result of giant asteroid impacts. A new terrestrial bombardment model, calibrated using existing lunar and terrestrial data, sheds light on the role asteroid collisions played in the evolution of the uppermost layers of the early Earth during the geologic eon called the "Hadean" (approximately 4 to 4.5 billion years ago).

Image above: An artistic conception of the early Earth, showing a surface pummeled by large impact, resulting in extrusion of deep seated magma onto the surface. At the same time, distal portion of the surface could have retained liquid water. Image Credit: Simone Marchi.

An international team of researchers from academic and government institutions, including NASA's Solar System Exploration Research Virtual Institute (SSERVI) at NASA's Ames Research Center in Moffett Field, California, published their findings in a paper, "Widespread Mixing and Burial of Earth's Hadean Crust by Asteroid Impacts" in the July 31, 2014 issue of Nature.

"A large asteroid impact could have buried a substantial amount of Earth's crust with impact-generated melt," said Yvonne Pendleton, SSERVI Director at Ames. "This new model helps explain how repeated asteroid impacts may have buried Earth's earliest and oldest rocks."

Terrestrial planet formation models indicate Earth went through a sequence of major growth phases: initially accretion of planetesimals – planetary embryos – over many tens of millions of years, then a giant impact by a large proto-planet that led to the formation of our moon, followed by the late bombardment when giant asteroids several tens to hundreds of miles in size periodically hit ancient Earth, dwarfing the one that killed the dinosaurs (estimated to be six miles in size) only 65 million years ago.

Researchers estimate accretion during the late bombardment contributed less than one percent of Earth's present-day mass, but the giant asteroid impacts still had a profound effect on the geological evolution of early Earth. Prior to four billion years ago Earth was resurfaced over and over by voluminous impact-generated melt. Furthermore, large collisions as late as about four billion years ago may have repeatedly boiled away existing oceans into steamy atmospheres. Despite the heavy bombardment, the findings are compatible with the claim of liquid water on Earth's surface as early as about 4.3 billion years ago based on geochemical data.

The new research reveals that asteroidal collisions not only severely altered the geology of the Hadean eon Earth, but likely also played a major role in the subsequent evolution of life on Earth as well.

"Prior to approximately four billion years ago, no large region of Earth's surface could have survived untouched by impacts and their effects," said Simone Marchi, SSERVI senior researcher at the Southwest Research Institute in Boulder, Colorado, and the paper's lead author. "The new picture of the Hadean Earth emerging from this work has important implications for its habitability."

Image above: Spatial distribution and sizes of craters formed on the early Earth. Each circle indicates the final estimated crater size. Color-coding indicates the time of impact. Image Credit: Simone Marchi et al. 2014.

Large impacts had particularly severe effects on existing ecosystems. Researchers found that on average, Hadean Earth more than four billion years ago could have been hit by one to four impactors that were more than 600 miles wide and capable of global sterilization, and by three to seven impactors more than 300 miles wide and capable of global ocean vaporization.

"During that time, the lag between major collisions was long enough to allow intervals of more clement conditions, at least on a local scale," said Marchi. "Any life emerging during the Hadean eon likely needed to be resistant to high temperatures, and could have survived such a violent period in Earth’s history by thriving in niches deep underground or in the ocean’s crust.”

The research was an international effort led by Marchi and William Bottke from the Southwest Research Institute in Boulder; Linda Elkins-Tanton from Carnegie Institution for Science in Washington; Michael Bierhaus and Kai Wünnemann from the Museum fur Naturkunde in Berlin, Germany; Alessandro Morbidelli from Observatoire de la Côte d'Azur in Nice, France, and David Kring from the Universities Space Research Association and Lunar and Planetary Institute in Houston.

The research was supported in part by SSERVI, a virtual institute that, with international partnerships, brings science and exploration researchers together in a collaborative virtual setting. SSERVI is funded by the Science Mission Directorate and Human Exploration and Operations Mission Directorate at NASA Headquarters in Washington.

For more information about SSERVI and selected member teams, visit: http://sservi.nasa.gov

Images (mentioned), Text, Credits: NASA / Ames Research Center / Rachel Hoover.

Best regards, Orbiter.ch

NASA's Fermi Space Telescope Reveals New Source of Gamma Rays

NASA - Fermi Gamma-ray Space Telescope logo.

July 31, 2014

Observations by NASA's Fermi Gamma-ray Space Telescope of several stellar eruptions, called novae, firmly establish these relatively common outbursts almost always produce gamma rays, the most energetic form of light.

Image above: These images show Fermi data centered on each of the four gamma-ray novae observed by the LAT. Colors indicate the number of detected gamma rays with energies greater than 100 million electron volts (blue indicates lowest, yellow highest). Image Credit: NASA/DOE/Fermi LAT Collaboration.

"There's a saying that one is a fluke, two is a coincidence, and three is a class, and we're now at four novae and counting with Fermi," said Teddy Cheung, an astrophysicist at the Naval Research Laboratory in Washington, and the lead author of a paper reporting the findings in the Aug. 1 edition of the journal Science.

A nova is a sudden, short-lived brightening of an otherwise inconspicuous star caused by a thermonuclear explosion on the surface of a white dwarf, a compact star not much larger than Earth. Each nova explosion releases up to 100,000 times the annual energy output of our sun. Prior to Fermi, no one suspected these outbursts were capable of producing high-energy gamma rays, emission with energy levels millions of times greater than visible light and usually associated with far more powerful cosmic blasts.

Fermi's Large Area Telescope (LAT) scored its first nova detection, dubbed V407 Cygni, in March 2010. The outburst came from a rare type of star system in which a white dwarf interacts with a red giant, a star more than a hundred times the size of our sun. Other members of the same unusual class of stellar system have been observed "going nova" every few decades.

Image above: The white dwarf star in V407 Cygni, shown here in an artist's concept, went nova in 2010. Scientists think the outburst primarily emitted gamma rays (magenta) as the blast wave plowed through the gas-rich environment near the system's red giant star. Image Credit: NASA's Goddard Space Flight Center/S. Wiessinger.

In 2012 and 2013, the LAT detected three so-called classical novae which occur in more common binaries where a white dwarf and a sun-like star orbit each other every few hours.

"We initially thought of V407 Cygni as a special case because the red giant's atmosphere is essentially leaking into space, producing a gaseous environment that interacts with the explosion's blast wave," said co-author Steven Shore, a professor of astrophysics at the University of Pisa in Italy. "But this can't explain more recent Fermi detections because none of those systems possess red giants."

Fermi detected the classical novae V339 Delphini in August 2013 and V1324 Scorpii in June 2012, following their discovery in visible light. In addition, on June 22, 2012, the LAT discovered a transient gamma-ray source about 20 degrees from the sun. More than a month later, when the sun had moved farther away, astronomers looking in visible light discovered a fading nova from V959 Monocerotis at the same position.

Astronomers estimate that between 20 and 50 novae occur each year in our galaxy. Most go undetected, their visible light obscured by intervening dust and their gamma rays dimmed by distance. All of the gamma-ray novae found so far lie between 9,000 and 15,000 light-years away, relatively nearby given the size of our galaxy.

Image above: Novae typically originate in binary systems containing sun-like stars, as shown in this artist's rendering. A nova in a system like this likely produces gamma rays (magenta) through collisions among multiple shock waves in the rapidly expanding shell of debris. Image Credit: NASA's Goddard Space Flight Center/S. Wiessinger.

Novae occur because a stream of gas flowing from the companion star piles up into a layer on the white dwarf's surface. Over time -- tens of thousands of years, in the case of classical novae, and several decades for a system like V407 Cygni -- this deepening layer reaches a flash point. Its hydrogen begins to undergo nuclear fusion, triggering a runaway reaction that detonates the accumulated gas. The white dwarf itself remains intact.

One explanation for the gamma-ray emission is that the blast creates multiple shock waves that expand into space at slightly different speeds. Faster shocks could interact with slower ones, accelerating particles to near the speed of light. These particles ultimately could produce gamma rays.

"This colliding-shock process must also have been at work in V407 Cygni, but there is no clear evidence for it," said co-author Pierre Jean, a professor of astrophysics at the University of Toulouse in France. This is likely because gamma rays emitted through this process were overwhelmed by those produced as the shock wave interacted with the red giant and its surroundings, the scientists conclude.

NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership managed by the agency's Goddard Space Flight Center in Greenbelt, Maryland. It was developed in collaboration with the U.S. Department of Energy, with contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.

For more information about Fermi, visit: http://www.nasa.gov/fermi

Related Links:

Paper: "Fermi Establishes Classical Novae as a Distinct Class of Gamma-Ray Sources": http://www.sciencemag.org/content/345/6196/554.abstract

"Fermi Detects 'Shocking' Surprise from Supernova's Little Cousin" (08.12.2010): http://www.nasa.gov/mission_pages/GLAST/news/shocking-nova.html

Imagine the Universe! Cataclysmic Variables: http://imagine.gsfc.nasa.gov/docs/science/know_l2/cataclysmic_variables.html

Images (mentioned), Text, Credits: NASA / J.D. Harrington / Goddard Space Flight Center / Lynn Chandler.

Cheers, Orbiter.ch

NASA Announces Mars 2020 Rover Payload to Explore the Red Planet as Never Before

NASA logo.

July 31, 2014

The next rover NASA will send to Mars in 2020 will carry seven carefully-selected instruments to conduct unprecedented science and exploration technology investigations on the Red Planet.

Image above: An artist concept image of where seven carefully-selected instruments will be located on NASA’s Mars 2020 rover. The instruments will conduct unprecedented science and exploration technology investigations on the Red Planet as never before. Image Credit: NASA.

NASA announced the selected Mars 2020 rover instruments Thursday at the agency's headquarters in Washington. Managers made the selections out of 58 proposals received in January from researchers and engineers worldwide. Proposals received were twice the usual number submitted for instrument competitions in the recent past. This is an indicator of the extraordinary interest by the science community in the exploration of the Mars. The selected proposals have a total value of approximately $130 million for development of the instruments.

The Mars 2020 mission will be based on the design of the highly successful Mars Science Laboratory rover, Curiosity, which landed almost two years ago, and currently is operating on Mars. The new rover will carry more sophisticated, upgraded hardware and new instruments to conduct geological assessments of the rover's landing site, determine the potential habitability of the environment, and directly search for signs of ancient Martian life.

"Today we take another important step on our journey to Mars," said NASA Administrator Charles Bolden.” While getting to and landing on Mars is hard, Curiosity was an iconic example of how our robotic scientific explorers are paving the way for humans to pioneer Mars and beyond. Mars exploration will be this generation’s legacy, and the Mars 2020 rover will be another critical step on humans' journey to the Red Planet."

Image above: Planning for NASA's 2020 Mars rover envisions a basic structure that capitalizes on the design and engineering work done for the NASA rover Curiosity, which landed on Mars in 2012, but with new science instruments selected through competition for accomplishing different science objectives. Mars 2020 is a mission concept that NASA announced in late 2012 to re-use the basic engineering of Mars Science Laboratory to send a different rover to Mars, with new objectives and instruments, launching in 2020. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, manages NASA's Mars Exploration Program for the NASA Science Mission Directorate, Washington. Image Credit: NASA/JPL-Caltech.

Scientists will use the Mars 2020 rover to identify and select a collection of rock and soil samples that will be stored for potential return to Earth by a future mission. The Mars 2020 mission is responsive to the science objectives recommended by the National Research Council's 2011 Planetary Science Decadal Survey.

“The Mars 2020 rover, with these new advanced scientific instruments, including those from our international partners, holds the promise to unlock more mysteries of Mars’ past as revealed in the geological record,” said John Grunsfeld, astronaut and associate administrator of NASA's Science Mission Directorate in Washington. “This mission will further our search for life in the universe and also offer opportunities to advance new capabilities in exploration technology.”

The Mars 2020 rover also will help advance our knowledge of how future human explorers could use natural resources available on the surface of the Red Planet. An ability to live off the Martian land would transform future exploration of the planet. Designers of future human expeditions can use this mission to understand the hazards posed by Martian dust and demonstrate technology to process carbon dioxide from the atmosphere to produce oxygen. These experiments will help engineers learn how to use Martian resources to produce oxygen for human respiration and potentially oxidizer for rocket fuel.

"The 2020 rover will help answer questions about the Martian environment that astronauts will face and test technologies they need before landing on, exploring and returning from the Red Planet," said William Gerstenmaier, associate administrator for the Human Exploration and Operations Mission Directorate at NASA Headquarters in Washington. "Mars has resources needed to help sustain life, which can reduce the amount of supplies that human missions will need to carry. Better understanding the Martian dust and weather will be valuable data for planning human Mars missions. Testing ways to extract these resources and understand the environment will help make the pioneering of Mars feasible."

The selected payload proposals are:

-   Mastcam-Z, an advanced camera system with panoramic and stereoscopic imaging capability with the ability to zoom. The instrument also will determine mineralogy of the Martian surface and assist with rover operations. The principal investigator is James Bell, Arizona State University in Phoenix.

-   SuperCam, an instrument that can provide imaging, chemical composition analysis, and mineralogy. The instrument will also be able to detect the presence of organic compounds in rocks and regolith from a distance. The principal investigator is Roger Wiens, Los Alamos National Laboratory, Los Alamos, New Mexico. This instrument also has a significant contribution from the Centre National d’Etudes Spatiales,Institut de Recherche en Astrophysique et Plane’tologie (CNES/IRAP) France.

-   Planetary Instrument for X-ray Lithochemistry (PIXL), an X-ray fluorescence spectrometer that will also contain an imager with high resolution to determine the fine scale elemental composition of Martian surface materials. PIXL will provide capabilities that permit more detailed detection and analysis of chemical elements than ever before. The principal investigator is Abigail Allwood, NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.

-   Scanning Habitable Environments with Raman & Luminescence for Organics and Chemicals (SHERLOC), a spectrometer that will provide fine-scale imaging and uses an ultraviolet (UV) laser to determine fine-scale mineralogy and detect organic compounds. SHERLOC will be the first UV Raman spectrometer to fly to the surface of Mars and will provide complementary measurements with other instruments in the payload. The principal investigator is Luther Beegle, JPL.

-   The Mars Oxygen ISRU Experiment (MOXIE), an exploration technology investigation that will produce oxygen from Martian atmospheric carbon dioxide. The principal investigator is Michael Hecht, Massachusetts Institute of Technology, Cambridge, Massachusetts.

-   Mars Environmental Dynamics Analyzer (MEDA), a set of sensors that will provide measurements of temperature, wind speed and direction, pressure, relative humidity and dust size and shape. The principal investigator is Jose Rodriguez-Manfredi, Centro de Astrobiologia, Instituto Nacional de Tecnica Aeroespacial, Spain.

The Radar Imager for Mars' Subsurface Exploration (RIMFAX), a ground-penetrating radar that will provide centimeter-scale resolution of the geologic structure of the subsurface. The principal investigator is Svein-Erik Hamran, Forsvarets Forskning Institute, Norway.

"We are excited that NASA's Space Technology Program is partnered with Human Exploration and the Mars 2020 Rover Team to demonstrate our abilities to harvest the Mars atmosphere and convert its abundant carbon dioxide to pure oxygen," said James Reuther, deputy associate administrator for programs for the Space Technology Mission Directorate. "This technology demonstration will pave the way for more affordable human missions to Mars where oxygen is needed for life support and rocket propulsion."

Instruments developed from the selected proposals will be placed on a rover similar to Curiosity, which has been exploring Mars since 2012. Using a proven landing system and rover chassis design to deliver these new experiments to Mars will ensure mission costs and risks are minimized as much as possible, while still delivering a highly capable rover.

Curiosity recently completed a Martian year on the surface -- 687 Earth days -- having accomplished the mission's main goal of determining whether Mars once offered environmental conditions favorable for microbial life.

The Mars 2020 rover is part the agency's Mars Exploration Program, which includes the Opportunity and Curiosity rovers, the Odyssey and Mars Reconnaissance Orbiter spacecraft currently orbiting the planet, and the MAVEN orbiter, which is set to arrive at the Red Planet in September and will study the Martian upper atmosphere.

In 2016, a Mars lander mission called InSight will launch to take the first look into the deep interior of Mars. The agency also is participating in the European Space Agency's (ESA’s) 2016 and 2018 ExoMars missions, including providing "Electra" telecommunication radios to ESA's 2016 orbiter and a critical element of the astrobiology instrument on the 2018 ExoMars rover.

NASA's Mars Exploration Program seeks to characterize and understand Mars as a dynamic system, including its present and past environment, climate cycles, geology and biological potential. In parallel, NASA is developing the human spaceflight capabilities needed for future round-trip missions to Mars.

NASA's Jet Propulsion Laboratory will build and manage operations of the Mars 2020 rover for the NASA Science Mission Directorate at the agency’s headquarters in Washington.

Related link:

Mars 2020 Rover and Beyond News Teleconference from NASA Headquarters in Washington DC: https://www.youtube.com/watch?v=1cRhU6bMLis&list=UULA_DiR1FfKNvjuUpBHmylQ

For more information about NASA's Mars programs, visit: http://www.nasa.gov/mars

Images (mentioned), Text, Credits: NASA / Dwayne Brown.

Best regards, Orbiter.ch

Hubble Shows Farthest Lensing Galaxy Yields Clues to Early Universe

NASA - Hubble Space Telescope patch.

July 31, 2014

Astronomers using NASA's Hubble Space Telescope have unexpectedly discovered the most distant galaxy that acts as a cosmic magnifying glass. Seen here as it looked 9.6 billion years ago, this monster elliptical galaxy breaks the previous record-holder by 200 million years.

Image above: The farthest cosmic lens yet found, a massive elliptical galaxy, is shown in the inset image at left. The galaxy existed 9.6 billion years ago and belongs to the galaxy cluster, IRC 0218. Image Credit: NASA and ESA.

These "lensing" galaxies are so massive that their gravity bends, magnifies, and distorts light from objects behind it, a phenomenon called gravitational lensing.  Finding one in such a small area of the sky is so rare that you would normally have to survey a region hundreds of times larger to find just one.

The object behind the cosmic lens is a tiny spiral galaxy undergoing a rapid burst of star formation. Its light has taken 10.7 billion years to arrive here and seeing this chance alignment at such a great distance from Earth is a rare find. Locating more of these distant lensing galaxies will offer insight into how young galaxies in the early universe build themselves up into the massive dark-matter-dominated galaxies of today. Dark matter cannot be seen, but it accounts for the bulk of the universe's matter.

"When you look more than 9 billion years ago in the early universe, you don't expect to find this type of galaxy lensing at all," explained lead researcher Kim-Vy Tran of Texas A&M University in College Station. "It's very difficult to see an alignment between two galaxies in the early universe. Imagine holding a magnifying glass close to you and then moving it much farther away. When you look through a magnifying glass held at arm's length, the chances that you will see an enlarged object are high. But if you move the magnifying glass across the room, your chances of seeing the magnifying glass nearly perfectly aligned with another object beyond it diminishes."

Team members Kenneth Wong and Sherry Suyu of Academia Sinica Institute of Astronomy & Astrophysics (ASIAA) in Taipei, Taiwan, used the gravitational lensing from the chance alignment to measure the giant galaxy's total mass, including the amount of dark matter, by gauging the intensity of its lensing effects on the background galaxy's light. The giant foreground galaxy weighs 180 billion times more than our sun and is a massive galaxy for its time. It is also one of the brightest members of a distant cluster of galaxies, called IRC 0218.

"There are hundreds of lens galaxies that we know about, but almost all of them are relatively nearby, in cosmic terms," said Wong, first author on the team's science paper. "To find a lens as far away as this one is a very special discovery because we can learn about the dark-matter content of galaxies in the distant past. By comparing our analysis of this lens galaxy to the more nearby lenses, we can start to understand how that dark-matter content has evolved over time."

Hubble orbiting Earth

The team suspects the lensing galaxy continued to grow over the past 9 billion years, gaining stars and dark matter by cannibalizing neighboring galaxies. Tran explained that recent studies suggest these massive galaxies gain more dark matter than stars as they continue to grow. Astronomers had assumed dark matter and normal matter build up equally in a galaxy over time, but now know the ratio of dark matter to normal matter changes with time. The newly discovered distant lensing galaxy will eventually become much more massive than the Milky Way and will have more dark matter, too.

Tran and her team were studying star formation in two distant galaxy clusters, including IRC 0218, when they stumbled upon the gravitational lens. While analyzing spectrographic data from the W.M. Keck Observatory in Hawaii, Tran spotted a strong detection of hot hydrogen gas that appeared to arise from a giant elliptical galaxy. The detection was surprising because hot hydrogen gas is a clear signature of star birth. Previous observations showed that the giant elliptical, residing in the galaxy cluster IRC 0218, was an old, sedate galaxy that had stopped making stars a long time ago. Another puzzling discovery was that the young stars were at a much farther distance than the elliptical galaxy. Tran was very surprised, worried and thought her team made a major mistake with their observations.

The astronomer soon realized she hadn't made a mistake when she looked at the Hubble images taken in blue wavelengths, which revealed the glow of fledgling stars. The images, taken by Hubble's Advanced Camera for Surveys and the Wide Field Camera 3, revealed a blue, eyebrow-shaped object next to a smeared blue dot around the massive elliptical. Tran recognized the unusual features as the distorted, magnified images of a more distant galaxy behind the elliptical galaxy, the signature of a gravitational lens.

To confirm her gravitational-lens hypothesis, Tran's team analyzed Hubble archival data from two observing programs, the 3D-HST survey, a near-infrared spectroscopic survey taken with the Wide Field Camera 3, and the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, a large Hubble deep-sky program. The data turned up another fingerprint of hot gas connected to the more distant galaxy.

The distant galaxy is too small and far away for Hubble to determine its structure. So, team members analyzed the distribution of light in the object to infer its spiral shape. In addition, spiral galaxies are more plentiful during those early times. The Hubble images also revealed at least one bright compact region near the center. The team suspects the bright region is due to a flurry of star formation and is most likely composed of hot hydrogen gas heated by massive young stars. As Tran continues her star-formation study in galaxy clusters, she will be hunting for more signatures of gravitational lensing.

The team's results appeared in the July 10 issue of The Astrophysical Journal Letters.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington.

For images and more information about Hubble, visit: http://www.nasa.gov/hubble and http://hubblesite.org/news/2014/33 and http://www.spacetelescope.org/

Image (mentioned), Video, Text, Credits:  NASA / J.D. Harrington / Space Telescope Science Institute / Donna Weaver/Ray Villard / ESA.

Greetings, Orbiter.ch

ALMA Finds Double Star with Weird and Wild Planet-forming Discs

ESO - European Southern Observatory logo.

30 July 2014

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have found wildly misaligned planet-forming gas discs around the two young stars in the binary system HK Tauri. These new ALMA observations provide the clearest picture ever of protoplanetary discs in a double star. The new result also helps to explain why so many exoplanets — unlike the planets in the Solar System — came to have strange, eccentric or inclined orbits. The results will appear in the journal Nature on 31 July 2014.

Artist’s impression of the discs around the young stars HK Tauri A and B

Unlike our solitary Sun, most stars form in binary pairs — two stars that are in orbit around each other. Binary stars are very common, but they pose a number of questions, including how and where planets form in such complex environments.

“ALMA has now given us the best view yet of a binary star system sporting protoplanetary discs  — and we find that the discs are mutually misaligned!” said Eric Jensen, an astronomer at Swarthmore College in Pennsylvania, USA.

The two stars in the HK Tauri system, which is located about 450 light-years from Earth in the constellation of Taurus (The Bull), are less than five million years old and separated by about 58 billion kilometres — this is 13 times the distance of Neptune from the Sun.

The young double star HK Tauri in the constellation of Taurus

The fainter star, HK Tauri B, is surrounded by an edge-on protoplanetary disc that blocks the starlight. Because the glare of the star is suppressed, astronomers can easily get a good view of the disc by observing in visible light, or at near-infrared wavelengths.

The companion star, HK Tauri A, also has a disc, but in this case it does not block out the starlight. As a result the disc cannot be seen in visible light because its faint glow is swamped by the dazzling brightness of the star. But it does shine brightly in millimetre-wavelength light, which ALMA can readily detect.

Using ALMA, the team were not only able to see the disc around HK Tauri A, but they could also measure its rotation for the first time. This clearer picture enabled the astronomers to calculate that the two discs are out of alignment with each other by at least 60 degrees. So rather than being in the same plane as the orbits of the two stars at least one of the discs must be significantly misaligned.

Wide-field view of part of the Taurus star formation region

“This clear misalignment has given us a remarkable look at a young binary star system,” said Rachel Akeson of the NASA Exoplanet Science Institute at the California Institute of Technology in the USA. “Although there have been earlier observations indicating that this type of misaligned system existed, the new ALMA observations of HK Tauri show much more clearly what is really going on in one of these systems.”

Stars and planets form out of vast clouds of dust and gas. As material in these clouds contracts under gravity, it begins to rotate until most of the dust and gas falls into a flattened protoplanetary disc swirling around a growing central protostar.

Composite views of HK Tauri from Hubble and ALMA

But in a binary system like HK Tauri things are much more complex. When the orbits of the stars and the protoplanetary discs are not roughly in the same plane any planets that may be forming can end up in highly eccentric and tilted orbits [1].

“Our results show that the necessary conditions exist to modify planetary orbits and that these conditions are present at the time of planet formation, apparently due to the formation process of a binary star system,” noted Jensen. “We can’t rule other theories out, but we can certainly rule in that a second star will do the job.”

The motions of material in the discs around the young double star HK Tauri

Since ALMA can see the otherwise invisible dust and gas of protoplanetary discs, it allowed for never-before-seen views of this young binary system. “Because we’re seeing this in the early stages of formation with the protoplanetary discs still in place, we can see better how things are oriented,” explained Akeson.

Looking forward, the researchers want to determine if this type of system is typical or not. They note that this is a remarkable individual case, but additional surveys are needed to determine if this sort of arrangement is common throughout our home galaxy, the Milky Way.

Zooming in on the young double star HK Tauri

Jensen concludes: “Although understanding this mechanism is a big step forward, it can’t explain all of the weird orbits of extrasolar planets — there just aren’t enough binary companions for this to be the whole answer. So that’s an interesting puzzle still to solve, too!”

Notes:

[1] If the two stars and their discs are not all in the same plane, the gravitational pull of one star will perturb the other disc, making it wobble or precess, and vice versa. A planet forming in one of these discs will also be perturbed by the other star, which will tilt and deform its orbit.

More information:

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Southern Observatory (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

This research was presented in a paper entitled “Misaligned Protoplanetary Disks in a Young Binary Star System”, by Eric Jensen and Rachel Akeson, to appear in the 31 July 2014 issue of the journal Nature.

The team is composed of Eric L. N. Jensen (Dept. of Physics & Astronomy, Swarthmore College, USA) and Rachel Akeson (NASA Exoplanet Science Institute, IPAC/Caltech, Pasadena, USA).

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning the 39-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Links:

Research paper: http://www.eso.org/public/archives/releases/sciencepapers/eso1423/eso1423a.pdf

NRAO press release about HK Tauri results: https://public.nrao.edu/news/pressreleases/young-binary-star-system-form-planets-with-weird-orbits

Image of HK Tauri from the NASA/ESA Hubble Space Telescope: http://www.spacetelescope.org/images/opo9905m/

More about ALMA: http://www.eso.org/public/teles-instr/alma/

Photos of ALMA: http://www.eso.org/public/images/archive/category/alma/

Videos of ALMA: http://www.eso.org/public/videos/archive/category/alma/

ALMA brochure: http://www.eso.org/public/products/brochures/alma_brochure_en/

The movie ALMA — In Search of our Cosmic Origins: http://www.eso.org/public/videos/eso1312a/

The ALMA Photo Book In Search of our Cosmic Origins – The Construction of the Atacama Large Millimeter/submillimeter Array: http://www.eso.org/public/products/books/alma-photobook/

More press releases with ALMA: http://www.eso.org/public/news/archive/search/?adv=&facility=36

Images, Text, Credits: ESO/ALMA/R. Hurt (NASA/JPL-Caltech/IPAC)/IAU and Sky & Telescope/Digitized Sky Survey 2. Acknowledgement: Davide De Martin/B. Saxton (NRAO/AUI/NSF); K. Stapelfeldt et al. (NASA/ESA Hubble)/NASA/JPL-Caltech/R. Hurt (IPAC)/Video: ESO/Digitized Sky Survey 2/N. Risinger (skysurvey.org). Music: movetwo.

Best regards, Orbiter.ch

Gaia: ‘Go’ for science

ESA - Gaia Mission patch.

29 July 2014

Following extensive in-orbit commissioning and several unexpected challenges, ESA’s billion-star surveyor, Gaia, is now ready to begin its science mission.

The satellite was launched on 19 December 2013, and is orbiting a virtual location in space 1.5 million kilometres from Earth.

Gaia’s goal is to create the most accurate map yet of the Milky Way. It will make extremely accurate measurements of the positions and motions of about 1% of the total population of roughly 100 billion stars in our home Galaxy to help answer questions about its origin and evolution.

Inside Gaia’s billion-pixel camera

Repeatedly scanning the sky, Gaia will observe each of its billion stars an average of 70 times each over five years. Small apparent motions in the positions of the stars will allow astronomers to determine their distances and movements through the Milky Way.

In addition, Gaia will also measure key physical properties of each star, including its brightness, temperature and chemical composition.

Gaia spins slowly once every six hours, sweeping its two telescopes across the sky and focusing the light from their separate fields simultaneously onto a single focal plane – the largest digital camera ever flown in space, with nearly a billion pixels.

As the stars drift across the camera, the relative positions of all detected stars are measured and downlinked to Earth. Over time, a complete network of positions of stars covering the whole sky is built up, before being analysed to yield a highly accurate 3D map.

The accuracy required is astonishing: Gaia must be able to measure positions to a level equivalent to the width of a human hair seen at 2000 km. In turn, these measurements demand a very rigorous calibration of the satellite and its instruments, a painstaking procedure that has taken the first part of the year to complete.

Gaia is now ready to begin its five-year science phase, but the commissioning also uncovered some unexpected anomalies.

One problem detected early in the commissioning was associated with water freezing on some parts of the optics, causing a temporary reduction in transmission of the telescopes.

This water was likely trapped in the spacecraft before launch and emerged once it was in a vacuum. Heating the affected optics to remove the ice has now largely solved this problem, but it is likely that one or two more ‘decontamination’ cycles will be required during the mission to keep it in check.

Another problem is associated with ‘stray light’ reaching Gaia’s focal plane at a level higher than predicted before launch. This appears to be a mixture of light from the Sun finding its way past Gaia’s 10 m-diameter sunshield and light from other astronomical objects, both making their way to the focal plane as a diffuse background.

Gaia spacecraft

The effect on Gaia’s performance is negligible for brighter objects at magnitude 15 and above, and a slight degradation in the positional accuracy is seen for fainter stars, reaching 50% for stars at Gaia’s nominal faint limit of magnitude 20.

There is also some effect on the accuracy to which stellar brightnesses will be measured.

The impact of the stray light should, in principle, be more significant for faint stars seen by Gaia’s Radial Velocity Spectrometer (RVS).

“However, we are optimising the onboard software to mitigate as much as possible the impact caused by these higher background levels of light, and we are confident that we will not be far off our initial and somewhat conservative estimate of studying 150 million stars with RVS, as planned,” says Giuseppe Sarri, ESA’s Gaia Project Manager.

“We will still be able to analyse one billion – if not more – stars with the astrometry and photometry instruments, measuring each star's position and motion up to 100 times more accurately than Gaia’s predecessor Hipparcos and for a far larger number of stars.”

Further tests made during commissioning have shown that it may be possible to extend Gaia’s reach to stars even fainter than magnitude 20, while at the other end, software changes enable Gaia to measure almost all of the brightest stars in the sky, previously ruled out as being too bright for such a sensitive system. Both of these extensions will need further analysis before being implemented.

Finally, Gaia also contains a laser device called the ‘basic angle monitor’, designed to measure the angle of separation between Gaia’s two telescopes to an extremely high level of accuracy. This is necessary in order to correct for expected periodic variations in the separation angle caused by thermal changes in the payload as Gaia spins.

Although this system is working, the detected variations in the basic angle are larger than expected. Further efforts are being made to measure and accurately calibrate the variations, with the aim of largely eliminating them during the overall data analysis.

The commissioning has not only focused on the spacecraft performance, but also on the flow of data on the ground, testing procedures that will be used to process and analyse the vast amount of data that will be transmitted to Earth on a daily basis for the next five years.

Thus, after extensive testing and analysis of systems both in space and on the ground, Gaia is now in a position to begin routine operations.

“The commissioning phase has been challenging, and although some activities are ongoing, all in all Gaia is in good shape to fulfil its promise – all of the core scientific goals are still achievable, as hoped,” says Timo Prusti, ESA’s Project Scientist for Gaia.

“Given the somewhat longer-than-expected commissioning and taking into account the time needed to develop some new software, we anticipate that the first intermediate catalogue of science data will be released to scientists and the public in summer 2016.

“However, if rapidly-changing objects such as supernovas are detected, open alerts will be made as soon as possible – a service we hope to have up and running before the end of this year.”

For a full quantitative analysis of Gaia’s expected science performance based on the results of commissioning, see http://www.cosmos.esa.int/web/gaia/news_20140729.

For updates published during the commissioning period, please refer to the Gaia blog: http://blogs.esa.int/gaia/

Related articles

How many stars are there in the Universe?: http://www.esa.int/Our_Activities/Space_Science/Herschel/How_many_stars_are_there_in_the_Universe

Eye of Gaia: billion-pixel camera to map Milky Way: http://orbiterchspacenews.blogspot.ch/2011/07/eye-of-gaia-billion-pixel-camera-to-map.html

Related links:

Gaia’s Radial Velocity Spectrometer (RVS): http://www.esa.int/Our_Activities/Space_Science/Gaia/Science_instruments

Gaia spacecraft testing: http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=31544&farchive_objecttypeid=31&farchive_objectid=30928

Vodcast: Charting the Galaxy - from Hipparcos to Gaia: http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=45772&fattributeid=885

Little books of Gaia: http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=35010

Make a Gaia model: http://www.rssd.esa.int/index.php?project=Gaia&page=Gaia_model

Explore stellar neighbourhood in 3D: http://workshop.chromeexperiments.com/stars/

Gaia launch campaign photos: http://sci.esa.int/gaia-launch-campaign-photos/

Image, Video, Text, Credit: ESA / C. Carreau.

Greetings, Orbiter.ch

Lifetime of gravity measurements heralds new beginning

ESA - GOCE Mission logo.

30 July 2014

Although ESA’s GOCE satellite is no more, all of the measurements it gathered during its life skirting the fringes our atmosphere, including the very last as it drifted slowly back to Earth, have been drawn together to offer new opportunities for science.

Carrying the first 3D gravity sensor in space, this state-of-the-art satellite measured Earth’s gravity with unprecedented accuracy.

GOCE

GOCE’s four years in orbit resulted in a series of four gravity models, each more accurate than the last. These models have been used to generate corresponding ‘geoids’ – the surface of a global ocean moulded  by gravity alone.

Shaped by differences in gravity, the geoid is a crucial reference for understanding ocean circulation, sea-level change and ice dynamics.

From a mission that just keeps giving, a fifth model has now been produced. It incorporates data collected throughout the satellite’s 42-month operational life.

The previous geoid, released in March 2013, was based on 27 months of measurements.

2011 GOCE geoid

The satellite was designed to orbit at an extremely low altitude of 255 km to gain the best possible gravity measurements. At the end of 2012, low fuel consumption allowed operators to extend its life and start to lower the satellite a further 31 km for even more accurate measurements. This was at the very limit of its capability but maximised the return for science.

After more than doubling its planned life in orbit, the satellite ran out of fuel and drifted back into the atmosphere in November 2013.

The fifth gravity model and geoid, which ESA has recently made available, includes these final precious measurements, right up until the satellite finally stopped working and ironically succumbed to the force it was designed to measure.

GOCE reenters atmosphere

Although the satellite is no longer in orbit, scientists now have the best possible information to hand about Earth’s gravity, effectively a new beginning for the mission.

GOCE has already shed new light on different aspects of Earth and surpassed its original scope in a number of ways.

It is being used to understand how oceans carry huge quantities of heat around the planet and to develop a global height reference system.

It has provided information about atmospheric density and winds, mapped the boundary between Earth’s crust and upper mantle, and used to understand what is going on in these layers far below our feet.

Moho and lithosphere

And its achievements include mapping a scar in Earth’s gravity caused by the 2011 Japanese earthquake.

The ultimate geoid model and gravity data will be used for years to come for a deeper understanding of Earth.

ESA’s GOCE Mission Manager, Rune Floberhagen, said, “We are very happy with the results of the final, super-low altitude phase of our mission.

Gravity scar over Japan

“In fact, efforts made by the mission team and by scientists to secure flight operations at these extreme altitudes and to process the data have resulted in a doubling of the information content and a very significant increase in spatial resolution.

“Indeed, our new ‘Release 5 solutions’ go well beyond the ambitious objectives we had when the GOCE project started.

“Scientists worldwide now have a satellite-based gravity field model at hand that will remain the de facto standard for many years to come.”

For more information about GOCE mission, visit: http://www.esa.int/Our_Activities/Observing_the_Earth/GOCE/

Access GOCE data: http://earth.esa.int/GOCE/

Images, Text, Credits: ESA/AOES Medialab/HPF/DLR/Bill Chater/GeoExplore STSE GOCE+ study team/DGFI/TU Delft.

Best regards, Orbiter.ch

Europe’s Fifth and Final Resupply Ship Launches to Station

ARIANESPACE / ESA - Flight VA219/ATV-5 Mission poster.


July 29, 2014

All systems are "green", Ariane 5 ECA and ATV-5 ready for launch

The European Space Agency’s (ESA) fifth and final Automated Transfer Vehicle (ATV-5) launched Tuesday atop an Ariane 5 rocket from Kourou, French Guiana, at 7:47 p.m. EDT. The ATV-5 will take a two week trip to the International Space Station docking to the Zvezda service module on Aug. 12 at 9:43 a.m. with 7 tons of science, food, fuel and supplies.

Final European resupply cargo ship begins its journey to the space station

The ATV-5 is named after the 20th century Belgian astronomer, Georges Lemaitre, who first proposed the expansion of the universe and applied Albert Einstein’s theory of general relativity to cosmology.

En route to the station, the Georges Lemaitre will pass 3.9 miles beneath the space station Aug. 8 so European flight controllers can test new rendezvous sensors. Engineers may use the new sensors in the design and manufacture of future European spacecraft. After the “fly-under”, the ATV-5 will pass in front, above and behind the station for the final four days of its rendezvous with Zvezda.

Liftoff  of Europe’s Fifth and Final Resupply Ship Launches to ISS

Image above: Europe's fifth Automated Transfer Vehicle launches on time from Kourou, French Guiana.

The ATV-5 is scheduled to depart the station next January filled with trash and discarded gear. However, the spacecraft will reenter the Earth’s atmosphere over the Pacific Ocean at a very shallow trajectory allowing the crew and ground controllers to monitor the reentry.

Ariane 5 second stage and ATV-5 Georges Lemaitre on way to ISS

The reentry technique is an exercise to gather data that may be used to monitor the International Space Station when it eventually deorbits. Cameras inside the ATV-5 from Europe, Japan and the United States, will record the breakup of the ATV-5.

Since the beginning of the year, seven resupply vehicles have visited the International Space Station replenishing its crews.

For more information about ARIANESPACE, visit: http://www.arianespace.com/index/index.asp

For more information about the Automated Transfer Vehicle (ATV), visit: http://www.esa.int/Our_Activities/Human_Spaceflight/ATV

Images, Video, Text, Credits: ARIANESPACE / ARIANESPACE TV / ESA / NASA / Orbiter.ch Aerospace.

Best regards, Orbiter.ch

Astronaut Mike Massimino Departs NASA for University Position

NASA patch.

July 29, 2014

After almost two decades with NASA, including two space shuttle missions, astronaut Mike Massimino left the space agency Monday for a full-time position with Columbia University in New York.

Massimino’s experience at NASA includes two shuttle missions to service the agency's Hubble Space Telescope. During the final servicing mission, STS-125 in 2009, Massimino became the first astronaut to tweet from space, which led to a significant social media following.

“Mike has played a significant role within the astronaut office in his time here,” said Bob Behnken, Chief of the Astronaut Office at NASA's Johnson Space Center in Houston. “His technical expertise was extremely helpful in the many roles he fulfilled, not the least of which was his part in the successful Hubble servicing missions.”

“Mike embraced the opportunity to engage with the public in new ways and set the stage for more space explorers to be able to share their mission experience directly with people around the globe. We wish him well in his new role fostering the dreams and innovations of students just beginning their career paths,” Behnken said.

Image above: Astronaut Michael J. Massimino, STS-109 mission specialist, peers into Columbia's crew cabin during a brief break in work on the Hubble Space Telescope, latched down just a few feet behind him in Columbia's cargo bay, during his second extravehicular activity of STS109 on March 5, 2002.
Image Credit: NASA.

A native of New York, Massimino earned his undergraduate degree from Columbia University and went on to accrue four additional degrees from the Massachusetts Institute of Technology in Cambridge, Massachusetts. He holds two master's degrees, one in mechanical engineering and a second in technology and policy, and a doctorate in mechanical engineering.

Massimino joined NASA in 1996. Prior to his first spaceflight assignment, he served in the Astronaut Office Robotics Branch and in the Astronaut Office Extravehicular Activity (EVA, or spacewalk) Branch. Following his first spaceflight, he served in 2002 as a spacecraft communicator in mission control and as the Astronaut Office Technical Liaison to Johnson’s EVA Program Office.

He also logged more than 570 hours in space, including 30 hours of spacewalks. His first mission was STS-109 in 2002, during which the seven-person Columbia crew successfully upgraded Hubble with a new power unit, Advanced Camera for Surveys, and solar arrays. STS-109 set a mission record for spacewalk time with 35 hours and 55 minutes over five spacewalks. Massimino performed two spacewalks during STS-109 totaling 14 hours and 46 minutes.

During STS-125, Massimino spent six days servicing and upgrading Hubble with the assistance of crewmates aboard shuttle Atlantis. STS-125 overtook the record set on STS-109, with 36 hours and 56 minutes over five spacewalks. Massimino’s spacewalks on this mission totaled 15 hours and 58 minutes.

For Astronaut Mike Massimino’s complete NASA biography, visit:
http://www.jsc.nasa.gov/Bios/htmlbios/massimin.html

Image (mentioned), Text, Credits: NASA / Stephanie Schierholz / Johnson Space Center / Nicole Cloutier-Lemasters.

Cheers, Orbiter.ch

ULA - Delta IV / AFSPC-4 success launch

ULA - Delta IV / AFSPC-4 Mission poster.


July 28, 2014

Image above: A United Launch Alliance Delta IV rocket, with the Air Force's AFSPC-4 mission aboard, is readied for launch from Space Launch Complex-37 at Cape Canaveral Air Force Station, Fla.

Monday, July 28, the launch of a United Launch Alliance Delta IV carrying the AFSPC-4 mission from Space Launch Complex (SLC)-37 at Cape Canaveral Air Force Station, Florida. Was launched at 6:43 p.m. EDT.

Launch of AFSPC-4 on Delta IV Rocket from Cape

The twin GSSAP spacecraft will support U.S. Strategic Command space surveillance operations as a dedicated Space Surveillance Network (SSN) sensor. The GSSAP will also support Joint Functional Component Command for Space (JFCC SPACE) tasking to collect space situational awareness data, allowing for more accurate tracking and characterization of man-made orbiting objects.

One of the two GSSAP spacecraft. Image Credit: USAF/SNC

The ANGELS satellite is managed by the Air Force Research Laboratory (AFRL) Space Vehicles Directorate. As part of AFRL’s research in advanced Space Situational Awareness (SSA), ANGELS examines techniques for providing a clearer picture of the environment surrounding our nation’s vital space assets.

AFSPC-4 was the 33rd ULA mission for the U.S. Air Force. It will be the eighth of 15 planned missions ULA is slated to launch in 2014, and ULA’s 85th since the company formed in 2006.

For more information abou United Launch Alliance (ULA), visit: http://www.ulalaunch.com/

Images, Video, Text, Credits: ULA/ULA TV/USAF/SNC.

Greetings, Orbiter.ch

Science and Spacesuit Work While ATV-5 Preps for Launch

ISS - Expedition 40 Mission patch.

July 28, 2014

The six-member Expedition 40 crew spent Monday on science work and spacesuit maintenance on the International Space Station. Meanwhile, on the ground in Kourou, French Guiana, the European Space Agency is counting down to Tuesday’s launch of its fifth and final Automated Transfer Vehicle atop on Ariane 5 rocket.

Commander Steve Swanson began his morning photographing astronauts Reid Wiseman and Alexander Gerst as they drew their own blood samples. Wiseman stowed those samples inside a science freezer for later analysis.

After his blood draws and sample stowage, Wiseman loaded software for the Human Research Facility-2 rack. The first time space flyer then assisted the commander throughout Monday on spacesuit maintenance. He started the spacesuit work scrubbing cooling loops and collecting a water sample for analysis. Next, he joined the commander for spacesuit inspection work.

Image above: Reid Wiseman sets up the Combustion Integrated Rack which includes an optics bench, combustion chamber, fuel and oxidizer control and five different cameras, allows a variety of combustion experiments to be performed safely aboard the station. Image Credit: NASA TV.

Read more about the Human Research Facility-2 rack: http://www.nasa.gov/mission_pages/station/research/experiments/60.html

Swanson also spent some time after his photography work removing alignment guides in the Combustion Integrated Rack. Afterward, he installed a plant experiment unit inside the Cell Biology Experiment Facility for the Resist Tubule botany experiment.

Read more about the Combustion Integrated Rack: http://www.nasa.gov/mission_pages/station/research/experiments/326.html

Read more about the Cell Biology Experiment Facility: http://www.nasa.gov/mission_pages/station/research/experiments/342.html

Read more about the Resist Tubule botany experiment: http://www.nasa.gov/mission_pages/station/research/experiments/966.html

The commander then spent the rest of the day on maintenance on one of the U.S. spacesuits. For his first task he filled the liquid cooling ventilation garment with water. Next he scrubbed the spacesuit and Quest airlock cooling loops of particulates and microbes. He collected a sample of the cooling loop water to determine the effectiveness of the scrubbing work. Swanson finally inspected the spacesuit’s sublimator and checked for water leaks.

Gerst, a German astronaut from the European Space Agency, spent most of his day on the Burning and Suppression of Solids (BASS-II) combustion experiment. He conducted two flame tests reducing the oxygen partial pressure in the Destiny laboratory’s Microgravity Science Glovebox (MSG) to create a stable blue flame with a long burn time. Scientists on the ground observed the work with cameras downlinking the video from inside the MSG.

Read more about the Burning and Suppression of Solids (BASS-II) combustion experiment: http://www.nasa.gov/mission_pages/station/research/experiments/1262.html

In between the BASS-II work, Gerst headed over to the Kibo laboratory to work inside the Kobairo experiment rack. Gerst then measured the insulation resistance of the racks’ Gradient Heating Furnace which is used to investigate crystal growth on semiconductors.

Veteran cosmonaut Alexander Skvortsov started his day with photography work for the Aseptic experiment which studies ways to sterilize space hardware. He then sampled and sterilized surfaces in the station’s Russian segment for the microbiology experiment. Skvortsov later worked on cargo ISS Progress 56 (56P) transfers inside the Pirs docking compartment and updated the inventory management system.

International Space Station (ISS). Image Credit: NASA

Flight Engineer Oleg Artemyev set up and worked throughout the day with the Kaskad experiment. The Russian study investigates the processes of cultivation of different types of cells and the technology to enable those processes. Artemyev also inventoried and stowed exercise clothes.

Upcoming Expedition 41 Commander Max Suraev started his day with 56P cargo transfers. Next he moved on to an experiment that explores using 3-D interactive manuals to train for experiments aboard the space station. Suraev then assisted Artemyev photographing his work for the Kaskad experiment. Finally, he participated in the Kaltsiy experiment, or Calcium, that observes bone demineralization in long-term space station crew members.

ESA’s fifth and final Automated Transfer Vehicle (ATV-5) will launch Tuesday atop an Ariane 5 rocket from Kourou, French Guiana, at 7:47 p.m. EDT. The ATV-5 will take a two week trip to the International Space Station docking to the Zvezda service module on Aug. 12 at 9:43 a.m. with 7 tons of science, food, fuel and supplies.

For more information about the International Space Station and its current crew, visit http://www.nasa.gov/station/

Images (mentioned), Text, Credit: NASA.

Cheers, Orbiter.ch

Cassini Spacecraft Reveals 101 Geysers and more on Icy Saturn Moon

NASA / ESA - Cassini "Insider's" logo.

July 28, 2014

Scientists using mission data from NASA’s Cassini spacecraft have identified 101 distinct geysers erupting on Saturn’s icy moon Enceladus.  Their analysis suggests it is possible for liquid water to reach from the moon’s underground sea all the way to its surface.

These findings, and clues to what powers the geyser eruptions, are presented in two articles published in the current online edition of the Astronomical Journal.

Over a period of almost seven years, Cassini’s cameras surveyed the south polar terrain of the small moon, a unique geological basin renowned for its four prominent "tiger stripe” fractures and the geysers of tiny icy particles and water vapor first sighted there nearly 10 years ago. The result of the survey is a map of 101 geysers, each erupting from one of the tiger stripe fractures, and the discovery that individual geysers are coincident with small hot spots. These relationships pointed the way to the geysers’ origin.

Image above: This artist's rendering shows a cross-section of the ice shell immediately beneath one of Enceladus' geyser-active fractures, illustrating the physical and thermal structure and the processes ongoing below and at the surface. Image Credit: NASA/JPL-Caltech/Space Science Institute.

After the first sighting of the geysers in 2005, scientists suspected repeated flexing of Enceladus by Saturn’s tides as the moon orbits the planet had something to do with their behavior. One suggestion included the back-and-forth rubbing of opposing walls of the fractures generating frictional heat that turned ice into geyser-forming vapor and liquid.

Alternate views held that the opening and closing of the fractures allowed water vapor from below to reach the surface. Before this new study, it was not clear which process was the dominating influence. Nor was it certain whether excess heat emitted by Enceladus was everywhere correlated with geyser activity.

To determine the surface locations of the geysers, researchers employed the same process of triangulation used historically to survey geological features on Earth, such as mountains. When the researchers compared the geysers’ locations with low-resolution maps of thermal emission, it became apparent the greatest geyser activity coincided with the greatest thermal radiation. Comparisons between the geysers and tidal stresses revealed similar connections. However, these correlations alone were insufficient to answer the question, “What produces what?”

The answer to this mystery came from comparison of the survey results with high-resolution data collected in 2010 by Cassini’s heat-sensing instruments. Individual geysers were found to coincide with small-scale hot spots, only a few dozen feet (or tens of meters) across, which were too small to be produced by frictional heating, but the right size to be the result of condensation of vapor on the near-surface walls of the fractures. This immediately implicated the hot spots as the signature of the geysering process.

Enceladus seen by Cassini. Image Credit: NASA/JPL-Caltech

“Once we had these results in hand we knew right away heat was not causing the geysers, but vice versa,” said Carolyn Porco, leader of the Cassini imaging team from the Space Science Institute in Boulder, Colorado, and lead author of the first paper. “It also told us the geysers are not a near-surface phenomenon, but have much deeper roots.”

Thanks to recent analysis of Cassini gravity data, the researchers concluded the only plausible source of the material forming the geysers is the sea now known to exist beneath the ice shell. They also found that narrow pathways through the ice shell can remain open from the sea all the way to the surface, if filled with liquid water. 

In the companion paper, the authors report the brightness of the plume formed by all the geysers, as seen with Cassini’s high resolution cameras, changes periodically as Enceladus orbits Saturn.  Armed with the conclusion the opening and closing of the fractures modulates the venting, the authors compared the observations with the expected venting schedule due to tides.

They found the simplest model of tidal flexing provides a good match for the brightness variations Cassini observes, but it does not predict the time when the plume begins to brighten. Some other important effect is present and the authors considered several in the course of their work.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory (JPL) in Pasadena, California, manages the mission for NASA's Science Mission Directorate in Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team consists of scientists from the United States, England, France and Germany. The imaging team is based at the Space Science Institute.

Additional details, images and an animation are available at: http://www.ciclops.org/view_event/202

More information about Cassini is available at: http://www.nasa.gov/cassini
and http://saturn.jpl.nasa.gov and http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens

Images (mentioned), Text, Credits: NASA / Dwayne Brown / JPL / Preston Dyches / Space Science Institute / Steve Mullins.

Best regards, Orbiter.ch